1. Field of the Invention
This invention is in the field of piston and cylinder internal combustion engines and particularly of fuel injectors for injecting slurry fuels into these engines.
2. Description of the Prior Art
Slurry Fuels comprising finely divided coal, suspended and stabilized in water, have been prepared and tested in piston and cylinder, diesel, internal combustion engines of the type used in railroad locomotives. An extensive literature exists describing these coal in water slurry (CWS) fuels, and the experimental results obtained when operating modified railroad locomotive diesel engines on these fuels. Some of this work is summarized in the following references:
A. "Coal Fueled Diesel Engines," edited by M. H. McMillian and H. A. Webb, ASME publication ICE Vol. 7, 1988;
B. "Coal Fueled Diesel Engines 1990," Edited by J. A. Caton, ASME publication ICE Vol 12, 1990;
C. "Coal Fueled Diesel Engines 1991," Edited by J. A. Caton and H. A. Webb, ASME publication ICE Vol. 14, 1991;
D. "Coal Fueled Diesel Engines 1993," Edited by J. A. Caton and H. A. Webb, ASME publication ICE Vol. 19, 1993;
Many of these engine experimental tests used a stabilized slurry of very finely divided coal particles in water with equal weights of coal and water. The finely divided coal was very low in sulfur and ash content. Nevertheless, the engine cylinder and piston rings experienced high wear rates, and the fuel injector nozzles experienced severe wear rates. The injection of such slurry fuels, at high pressure and high velocity, through the small diameter injector nozzles, appeared to cause rapid wear away of the nozzle material. Even when sapphire injector nozzles were used the wear rate, while reduced, was still adversely high.
Much of this prior art work, using coal in water slurry fuels, was sponsored by the U.S. Department of Energy in an effort to develop satisfactory alternative fuels to replace petroleum based fuels. In recent years the U.S. has become increasingly, and heavily, dependent on imported petroleum fuels, thus creating a balance of trade problem, and a national defense weakness. Additionally coal is less expensive per unit of energy than are petroleum derived fuels and fuel cost savings could be achieved by substituting coal water slurry fuels for petroleum fuels. It would thus be desirable to have available a fuel injector system for slurry fuels which did not have the severe injector wear problems of prior art slurry fuel injectors.
3. Definitions
The term piston internal combustion engine is used herein and in the claims to mean an internal combustion engine of the piston and cylinder type, with connecting rod and crankshaft or equivalent, such as the Wankel engine type, or opposed piston type engines, and comprising:
At least one combined means for compressing and expanding gases, each combined means comprising: an internal combustion engine mechanism comprising a variable volume chamber for compressing and expanding gases, and drive means, such as a connecting rod and crankshaft, for driving said internal combustion engine mechanism and varying the volume of said chamber through repeated cycles.
Each variable volume chamber comprises a combustion chamber end at the minimum volume position of the variable volume.
Each variable volume cycle comprises a compression time interval, when said variable volume is sealed and decreasing, followed by an expansion time interval, when said variable volume is sealed and increasing, these two time intervals together being a compression and expansion time interval.
Each combined means for compressing and expanding further comprises intake means for admitting reactant gases into said variable volume chamber prior to each compression time interval and exhaust means for removing reacted gases from said variable volume chamber after each expansion time interval.
Each variable volume cycle further comprises an exhaust time interval, when said variable volume is opened to said exhaust means, followed by an intake time interval, when said variable volume is opened to said intake means, these two time intervals being an exhaust and intake time interval; said exhaust and intake time interval following after a preceding expansion time interval and preceding a next following compression time interval. For a four stroke cycle piston internal combustion engine each separate time interval occupies approximately one half engine revolution and thus one stroke of the piston. For a two stroke cycle piston internal combustion engine the expansion time interval together with the exhaust time interval occupy approximately a half engine revolution and one piston stroke, and an intake time interval followed by a compression time interval occupy the next following half engine revolution and piston stroke.
A piston internal combustion engine further comprises a source of supply of reactant gas containing appreciable oxygen gas to each said intake means for admitting reactant gases into said variable volume chamber.
The combustion time interval is that portion of the compression and expansion time interval when burning of the air fuel mixture in the engine cylinder is intended to take place. For reasons of engine efficiency, this combustion time interval is preferably intended to occur when the variable volume chamber is at or near to its minimum volume, during or following a compression time interval.
The term reactant gas containing appreciable oxygen gas is used herein and in the claims to mean a reactant gas having a ratio of oxygen gas to inert gases at least about equal to that for air, and which may additionally comprise a principal engine fuel.
The term piston crown is used herein and in the claims to mean that portion of the structure of an engine piston on the variable volume side of the piston.